Tangential Flow Filtration (TFF) FAQ

Information applicable to use of Pall membrane devices, hardware and systems for tangential flow filtration.


Do I need a holder to use the Single-Use TFF (SUTFF) modules? Can it be used without a holder?

Yes, the SUTFF module requires a SUTFF module holder.  The SUTFF module must be placed in the SUTFF module holder and compressed to activate the seals.  The SUTFF module will leak if it is used without a module holder.  Refer to FAQ: What is the part number of the SUTFF module holder?

What is the recommended torque value for installing the Single-Use TFF (SUTFF) modules in the SUTFF module holder?
Does the cassette integrity test confirm the molecular weight cut-off (MWCO) of the membrane? If not, what does the integrity test tell me?

No.  The membrane MWCO cannot be verified by the cassette integrity test.  The cassette integrity test cannot differentiate between a 10kD and 100kD membrane.  The membrane MWCO is verified by the solute passage test.  The membrane integrity test confirms if the cassette has been installed properly into the cassette holder, the torque has been applied sufficiently to activate the external seals, and there are no gross leaks on the membrane. 


Cadence® Single-Use Tangential Flow Filtration (TFF) Modules

Suspended-Screen Ultrafiltration Cassettes with Omega™ Membrane: Centramate™ and Centrasette™ II Cassettes

T-Series TFF Cassettes with Delta Membrane

T-Series TFF Cassettes with Omega™ Membrane

I have a Centramate / Centrasette cassette holder. Can I use it with the Single-use (SUTFF) modules or do I need to purchase a different cassette holder?

The SUTFF modules require a SUTFF module holder which is different from the Centramate or Centrasette cassette holder.  The Centramate and Centrastte cassette holders have built-in ports for feed, retentate, and permeate.  In SUTFF, these ports are located on one of the SUTFF module endplates, and there are no ports on the module holder.     

Proposed Pall website location (by product assignment):

Cadence® Single-Use Tangential Flow Filtration (TFF) Modules

Can I re-use the Single-Use TFF (SUTFF) modules? If yes, how can I clean the module and store the post-use modules?

The Cadence® Single-Use Tangential Flow Filtration (TFF) Modules is intended for single-use only. There is no claim for re-using SUTFF module.

The Single-Use TFF (SUTFF) modules are gamma-irradiated with ≥ 25 kGy. Does this mean the SUTFF modules are sterile?

No. There is no sterility claim on our Cadence® Single-Use Tangential Flow Filtration (TFF) Modules. The SUTFF modules are gamma-irradiated to reduce the bioburden and to be able to use water as the storage solution. The SUTFF module needs to be sanitized during the pre-use conditioning step.

Do you have the Single-Use TFF (SUTFF) Module with 300 kDa Omega™ membrane?

No. The pre-assembled Cadence® Single-Use Tangential Flow Filtration (TFF) Modules are only available for 10kDa, 30 kDa, and 100 kDa Omega membranes.  The 300 kDa membrane is not a standard offering. If other molecular weight cut-offs are required, the end-user can evaluate the customized SUTFF module.  In the customized SUTFF assembly, standard Pall cassettes MWCO’s are offered and the module endplates and/or the flow distribution plates come separately. The end-user can assemble the SUTFF module on site.

What is the Hold Up Volume of the T-series TFF Cassettes?

Estimated Hold-up Volumes of T-Series TFF Cassettes with Omega™ Membrane

t series volume faq

Note that it is imperative to determine the total hold-up volume for the TFF system following installation of cassettes. Most of it is recoverable, it contains the cassette, holder, and the feed/retentate flow path. This is describedin the User Guide USTR 2433b – page 18 - § 3.3 Hold-up Volume and Minimum Working Volume

How do I integrity test a Pall Tangential Flow Filter (TFF) cassette?

The following description it is not intended as an instruction for use, but rather a summary on the test.

Refer to section 4.6, page 31 “System and Membrane Cassette Integrity Test” of the T-series Cassette Care and Use Procedure USTR 2433b for detailed instructions and the image for the connections.

This Integrity test method is recommended for ultrafiltration membrane with a Molecular Weight Cut-Off (MWCO) of≤ 300 kDa.

1.1 General Procedure

The cassette should be fully wetted out with water prior to conducting the integrity test.  A clean compressed air source should be connected to the feed line, with an isolation valve between the pump and the air inlet line.  The compressed air source requires a regulator that can be controlled to the recommended test pressure with a mass flow meter installed in the air line upstream of the filter. Alternatively, an integrity test instrument can be used if it is capable of measuring the require diffusive flow.

Ensure that the system is fully drained.  Set the pressure on the regulator or integrity test instrument to the specified test pressure for the specific membrane being used.  The retentate valve and the isolation valve between the pump and air inlet should be completely closed, with the permeate valve completely open.

Turn on the air supply to slowly (~15 - 30 seconds), pressurize the system to the recommended test pressure.  The diffusive flow rate will initially increase before it drops and levels off at a stable flow rate.If this stable flow value is below the maximum allowable value for the particular membrane being tested, the integrity test is deemed to have a passing result.

If this value is greater than the maximum allowable value, then the test should be repeated with the permeate valve closed.  This will test the system for any leaks and will help determine if the failure is due to a system leak versus a non-integral membrane.  When testing the system for external leaks, the diffusive flow rate should be < 5 sccm.  It may take 15 minutes or longer for the flow rate to stabilize to this point on some systems, as the permeate side of the system is relying on diffusive flow through the membrane to pressurize.

1.2 Diffusive flowrate measurement

In order to measure the diffusive flow, the useof an integrity test instrument or a flowmeter are the best ways, but in some cases if these instruments are not available, it is possible use the following procedure:

1.  For a large-scale system, when maximum measurable diffusive flow ratefor theintegrity test instrument is higherthan the allowable limit, it may bepossible to perform the test using apressure decay value. This value is calculated from a formula that transforms the diffusive flowrate limit toa pressure decay limit. To obtain pressure decay limits for your assembly, please contact Pall.

2. For small, bench scale systems, when the diffusive flowrate is≤ 100 cc/min, it is possible to measure the flow manually measuring the displaced byplacing the permeate line into an inverted graduated burette in a beaker with water (refer to Figure 1). The volume of air displaced versus time will indicate the diffusive flow rate. With this method, it is a best practice to take multiple measurements in order to confirm the integrity of the system.

integrity test faq

1.3 How to calculate the flowrate limit

The test limit should be calculated from the data in the table 1:

integrity test parameters

Example: for a 10 kDa cassette with 1.5 m2 of membrane area the calculation is the following:

1600 sccm/m2 x 1.5 m2 = 2400 sccm, where 1 sccm is a standard cubic centimeters per minute, so the final result is ≤2400 mL/min.

Test will be performed at 2.0 barg (or 30 psig) and the test limit is ≤2400 mL/min. 

What is the integrity test specification for Single-Use TFF (SUTFF) Modules?

The Cadence® Single-Use Tangential Flow Filtration (TFF) Modules (P/N: CSUMxxxTxxx) have the fixed membrane area.  The customized SUTFF modules may have more than one cassette installed.  The total membrane area can be calculated by multiplying the membrane area of each cassette by the total number of cassettes installed. 

Forward Flow integrity specification for the Cadence® Single-Use Tangential Flow Filtration (TFF) Modules Modules with T-series Omega™ membrane is ≤ 1600 sccm/m2 (150 sccm/ft2) at 2.0 barg (30 psig) test pressure. The unit sccm means standard cubic centimeters per minute. 

To calculate the maximum allowable air flow rate, multiply the total membrane area in the cassette holder by the Forward Flow integrity specification. 

For example, four Omega OS030T06 cassettes are installed in the customized SUTFF module holder.  The total membrane area is 2.0 m2.  The maximum allowable air flow rate is 3200 sccm or 3200 mL/min.

Airflow rate=(Membrane area)×(Number of cassettes)×(Integrity specification)

Airflow rate=(0.5m^2 )×(4)×(1600 sccm/m^2 )=3200 sccm

Please refer to Pall Publication:

USTR 2896 Instructions For Use - “Cadence™ Single-Use Tangential Flow Filtration (TFF) Modules with Omega™ Membrane”

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